Biogen Idec Inc. said its fourth-quarter profit nearly doubled, as its portfolio of multiple sclerosis treatments drove a 34% growth in revenue.

Shares of Biogen surged in after-hours trading as the biotech’s earnings in the fourth quarter and its projection for 2015 surpassed analysts’s expectations. The stock, up 16% over the past year through the close Thursday, rose more than 6% in recent after-hours trading to $375.20, which would be above the 52-week high of $366.17 set during regular trading on Jan. 21.